The problem of spam in established communication technologies, such as electronic mail, is well-recognized. Spam may include unsolicited messages sent by a computer over a network to a large number of recipients. In some cases, spam messages may be sent to a targeted user or targeted domain, for malicious, disruptive, or abusive purposes. For example, a spammer might send messages in bulk to a particular domain to exhaust its resources. Therefore, it may be beneficial to determine whether or not a message is spam and filter it accordingly. However, it may be difficult to determine whether or not a message is spam based on the sender and/or content of the message. One possible way of determining if a message is spam may be through an anti-spam system. These anti-spam systems may use user feedback to determine if the message is spam or not and filter it accordingly.
One possible problem with user feedback is that the user may not always be truthful or accurate as to whether the message is actually spam or not. For example, a user might signup for a distribution list that sends coupon messages to users. At some later date, the user may decide that he or she does not want to receive coupon messages anymore and may mark a coupon message as spam. Although the coupon message may be unwanted by that user, it may not be spam to other users who sign up for the distribution list. Therefore, the anti-spam system may receive inaccurate user feedback from some users. Similarly, some inaccurate user feedback may come from the spammer themselves. In some situations, spammers may hire humans and/or create robot accounts to provide inaccurate feedback in an attempt to misguide an anti-spam system so that a spam message is treated as non-spam. Thus, it is with respect to these considerations and others that the present invention has been made.